3-(4-Nitrophenyl)-N-phenyloxirane-2-carboxamide

The molecule of the title compound, C15H12N2O4, adopts a syn conformation with the terminal benzene rings located on the same sides of the central epoxide ring. The epoxide ring makes dihedral angles of 71.08 (18) and 60.83 (17)° with the two benzene rings. Weak intermolecular C—H⋯O hydrogen bonding is present in the crystal structure.

The molecule of the title compound, C 15 H 12 N 2 O 4 , adopts a syn conformation with the terminal benzene rings located on the same sides of the central epoxide ring. The epoxide ring makes dihedral angles of 71.08 (18) and 60.83 (17) with the two benzene rings. Weak intermolecular C-HÁ Á ÁO hydrogen bonding is present in the crystal structure.

S1. Comment
Oxiranecarboxamides are the key building blocks in the synthesis of natural products such as the Taxol side chain (Righi et al. 1996). Selective ring-opening reactions of oxiranes also provide powerful and efficient routes to a variety of useful compounds including 2,3-epoxyketone (Meth-Cohn et al. 1999), aziridinecarboxylate (Thijs et al. 1990). isoserine derivatives (Bhatia et al. 1999). The crystal structure of the title compound is reported here.
The molecular structure of (I) is shown in Fig. 1. Bond lengths and angles in (I) are normal. The two phenyl ring is the cis conformation, the dihedral angle between the two phenyl ring is 77.34 (8)°. Epoxide ring makes dihedral angles of 71.08 (18)° and 60.83 (17)° with phenyl rings C1-C6 and C10-C15, respectively. The crystal packing is stabilized by C-H···0 hydrogen bonding (Table 1).

S2. Experimental
2-Chloro-N-phenylacetamide (0.17 g, 1.0 mmol) and sodium ethanolate (0.14 g, 2.0 mmol) were dissolved in acetonitrile (2 ml). To the solution was added 4-nitrophenylaldehyde (0.15 g, 1.0 mmol) at 298 K, the solution was stirred for 60 min and removal of solvent under reduced pressure, the residue was purified through column chromatography on silica gel to give compound (I). Crystals suitable for X-ray analysis were obtained by dissolving the title compound (0.01 g) in ethanol (2 ml) and evaporating the solvent slowly at room temperature for about 3 d.

S3. Refinement
The H4 atom was located in a difference Fourier map and refined isotropically. The carbon-bound hydrogen atoms were placed in calculated positions with C-H = 0.93-0.98 Å, and refined using a riding model with U iso (H) =1.2U eq (C).
Friedel pairs were merged.  The molecular structure of (I) with 30% probability displacement ellipsoids (arbitrary spheres for H atoms).

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.